A species of gecko, a small, brilliantly coloured lizard, has the back of its tail armed with plates. These it has a habit of rubbing together, and by this means it produces a shrill, chirruping sound, which actually attracts crickets and grasshoppers toward the noise, so that they fall easy prey to this reptilian trapper. So in colour, sound, motion, and many other ways, animals act and react upon each other, a useful and necessary habit being perverted by an enemy, so that the death of the creature results. Yet it would never be claimed that the lizard thought out this mimicking. It probably found that certain actions resulted in the approach of good dinners, and in its offspring this action might be partly instinctive, and each generation would perpetuate it. If it had been an intentional act, other nearly related species of lizards would imitate it, as soon as they perceived the success which attended it.
That many animals have a kind of language is nowadays admitted to be a truism, but this is more evident among mammals and birds, and, reviewing the classes of the former, we find a more or less defined ascending complexity and increased number of varying sounds as we pass from the lower forms—kangaroos and moles—to the higher herb-and-flesh-eaters, and particularly monkeys.
Squeaks and grunts constitute the vocabulary, if we dignify it by that name, of the mammals. The sloths, those curious animals whose entire life is spent clinging to the underside of branches, on whose leaves they feed, may be said almost to be voiceless, so seldom do they give utterance to the nameless wail which constitutes their only utterance. Even when being torn to pieces by an enemy, they offer no resistance and emit no sound, but fold their claws around their body and submit to the inevitable as silently and as stoically as did ever an ancient Spartan.
Great fear of death will often cause an animal to utter sounds which are different from those produced under any other conditions. When an elephant is angry or excited, his trumpeting is terribly loud and shrill; but when a mother elephant is “talking” to her child, while the same sonorous, metallic quality is present, yet it is wonderfully softened and modulated. A horse is a good example of what the fear of death will do. The ordinary neigh of a horse is very familiar, but in battle when mortally wounded, or having lost its master and being terribly frightened, a horse will scream, and those who have heard it, say it is more awful than the cries of pain of a human being.
Deer and elk often astonish one by the peculiar sounds which they produce. An elk can bellow loudly, especially when fighting; but when members of a herd call to each other, or when surprised by some unusual appearance, they whistle—a sudden, sharp whistle, like the tin mouthpieces with revolving discs, which were at one time so much in evidence.
The growl of a bear differs greatly under varying circumstances. There is the playful growl, uttered when two individuals are wrestling, and the terrible “sound”—no word expresses it—to which a bear, cornered and driven to the last extremity, gives utterance—fear, hate, dread, and awful passion mingled and expressed in sound. One can realise the fearful terror which this inspires only when one has, as I have, stood up to a mad bear, repelling charge after charge, with only an iron pike between one’s self and those powerful fangs and claws. The long-drawn moan of a polar bear on a frosty night is another phase; this, too, is expressive, but only of those wonderful Arctic scenes where night and day are as one to this great seal-hunter.
The dog has made man his god,—giving up his life for his master would be but part of his way of showing his love if he had it in his power to do more. So, too, the dog has attempted to adapt his speech to his master’s, and the result is a bark. No wild coyotes or wolves bark, but when bands of dogs descended from domesticated animals run wild, their howls are modulated and a certain unmistakable barking quality imparted. The drawn-out howl of a great gray wolf is an impressive sound and one never to be forgotten. Only the fox seems to possess the ability to bark in its native tongue. The sounds which the cats, great and small, reproduce are most varied. Nothing can be much more intimidating than the roar of a lion, or more demoniacal than the arguments which our house-pets carry on at night on garden fences.
What use the sounds peculiar to sea-lions subserve in their life on the great ocean, or their haunts along the shore, can only be imagined, but surely such laudable perseverance, day after day, to out-utter each other, must be for some good reason!
Volumes have been written concerning the voices of the two remaining groups of animals—monkeys and birds. In the great family of the four-handed folk, more varieties of sound are produced than would be thought possible. Some of the large baboons are awful in their vocalisations. Terrible agony or remorse is all that their moans suggest to us, no matter what frame of mind on the part of the baboon induces them. Of all vertebrates the tiny marmosets reproduce most exactly the chirps of crickets and similar insects, and to watch one of these little human faces, see its mouth open, and instead of, as seems natural, words issuing forth, to hear these shrill squeaks is most surprising. Young orang-utans, in their “talk,” as well as in their actions, are counterparts of human infants. The scream of frantic rage when a banana is offered and jerked away, the wheedling tone when the animal wishes to be comforted by the keeper on account of pain or bruise, and the sound of perfect contentment and happiness when petted by the keeper whom it learns to love,—all are almost indistinguishable from like utterances of a human child.
But how pitiless is the inevitable change of the next few years! Slowly the bones of the cranium thicken, partly filling up the brain cavity, and slowly but surely the ape loses all affection for those who take care of it. More and more morose and sullen it becomes until it reaches a stage of unchangeable ferocity and must be doomed to close confinement, never again to be handled or caressed.